The effect of fragrances on your mind and emotions may be subtle, but they can make you feel better about yourself. Scent can improve your mood, reduce stress, cause you to become more energetic, or help you relax or fall asleep more easily.
Peppermint is a stimulating scent that can intensify brain waves to sharpen the mind and quicken your reactions. This action is very similar to what happens if you drink coffee, but without any caffeine. Your teachers' suggestion to surround yourself with the scent of peppermint while you study is intended to help you stay alert and focus on your homework so that you can work more quickly and easily.
Even if you don't think that this aromatherapy is working on you, keep in mind that creating a study routine of any type (whether it involves a special candle, soft music, sitting in a particular spot, or using a favorite pen) can really help to put yourself in a more productive frame of mind.